Wash lights, as they are generally known, are used to provide uniform illumination and coloration to a theatrical set. Numerous lighting fixtures have been provided in the past wherein the output of the light source and reflector are selectively colored by the positioning of one or more colored media in front of the light beam. Some of these applications have included a strip of media moved across a light beam, a scrolling variable density gel media device, and gradient density color wheels. None of these variable density filters address or consider the power density of the light beam. They do not compensate for the non-linear distribution of light intensity across a light beam which results from the use of a more efficient elliptical reflector, As a result, when used with such a reflector. A linear distribution color wheel will provide a nonlinear coloration of the light beam, which is darker at the edges and perceptibly lighter toward the center of the beam. A ratio of power from center of beam to beam edge is often on the order of 50%. Variable density filters which do not address the power density of the beam produce results which are non-uniform and leave an apparent white spot in the center of the beam while darkening the edge first. This accentuates the power gradient shift and makes the resultant coloration more objectionable. A further complication of this approach is that fully saturated colors cannot be used due to excessive transmission losses at fractional percentages or an exaggeration of the power density losses.
Prior art lights of the type contemplated by this invention most often utilize two moving lenses or a moving light source with a single lens and require substantial space and complex mechanical slide systems. These limitations make it difficult to provide a fixture of a compact size.
Heat dissipation is always a critical consideration in lighting fixtures, Many fixtures utilize a hot mirror reflector which is, at best, fifty percent efficient in controlling the infrared heat energy. Fan cooling is therefore typically required for an additional heat transfer capability in conventional stage and studio lighting which again detracts from a compact fixture. Also typical of such fixtures is the lack of a module based design so that, for example, the addition or removal of control and sensor functions requires redesign of the system hardware.
Lights used in a studio or for photographic purposes often project a round cross-sectional pattern of light such as that seen by the ordinary flashlight. Simple devices utilize a reflector and a lamp or utilize sealed beam lamps, such as automotive head light type lamps. These sealed lamps consist of a reflector, a lamp and a type of diffuser or lens to soften the projected spot, and sometimes to focus the projected spot from either a narrow spot or a wide flood. More complicated arrangements involve ellipsoidal reflectors or condensing systems which focus light through an aperture which is imaged by projector lenses. These types of systems commonly produce a more uniform beam of light than that of the sealed beam type. Other types of lights used include fresnel projectors, which utilize a fresnel projecting lens. The fresnel projecting lens is known to provide a beam of light that is homogenous with a gradual rolloff of light output toward the edges. Many of the things illuminated on a stage or studio do not always require a round beam of light since many stages or studio sets can often be more wide than they are tall. Illuminated subject areas often require the use of a framing projector or devices known as barn doors which can be utilized to change cross-sectional pattern or the shape of the beam by shadowing the light projected from the device as a means to change the shape of the beam.
The foregoing illustrates limitations of the known prior art. Thus it is apparent that it would be advantageous to provide alternatives directed to overcoming one or more of the limitations as set forth above. Accordingly, suitable alternatives are provided including features and benefits more fully disclosed hereinafter.